1. Field of the Invention
The present invention relates to a method and an apparatus which controls write power in an optical drive, and more particularly, to a method and an apparatus which controls the write power by optimizing the number of channels used to drive a laser diode (LD) in response to performing a writing mode.
2. Description of the Related Art
An optical drive is a device which records/reads data into/from a disk, such as a compact disk or a digital versatile disk. A conventional optical drive stops writing data in an emergency, such as buffer under run, during a write operation, and thus it is not able to write the data normally. Accordingly, techniques to restart the write operation, at a point where the writing of the data is stopped, while performing a write mode have been suggested to obtain normally written data.
However, there is a time difference between the time when the write mode is controlled and the time when a power voltage output from an auto laser diode power control (APC) circuit reaches a stable level. Accordingly, in the case of retrying to write data at a point where the writing of the data is stopped, the writing of the data is generated before the power voltage of the APC circuit reaches the stable level, and therefore hinders the data from being normally written. Thus, some of the data may be lost.
To solve this problem, a technique of stabilizing a voltage of write power at an early stage of a write mode has been suggested. The voltage of the write power is stabilized at an early stage by adding a predetermined percentage of an expected power voltage output from an APC circuit to the expected power voltage of the APC circuit after controlling the write mode.
However, this technique must use an additional channel to drive an LD to add the predetermined percentage of the expected power voltage of the APC circuit to the expected power voltage of the APC circuit. Accordingly, although this technique may stabilize the voltage of the write power and prevent the data from being lost at an early stage of the write mode, such an optical drive must manage the additional channel which becomes unnecessary after the stabilization of the write power voltage. Additionally, the size of a firmware in the optical driver is increased. Furthermore, in the case of controlling a write mode according to this technique, it is impossible to control the voltage of the write power at a level lower than the predetermined percentage of the expected power voltage of the APC circuit while performing the write mode.